1. Field of the Invention
The present invention relates to an object state identification method, an object state identification apparatus, and a carrier including an object state identification apparatus to identify the state of an object such as the position and posture thereof. In particular, the present invention relates to an object state identification method, an object state identification apparatus, and a carrier, each of which identifies an object state indicating the position, posture, etc., of an object including a flat portion including an opening on a surface of the object when an automated guided carrier or the like holds the object.
2. Description of the Related Art
Various object state identification methods for identifying an object state based on information of an image captured of an object have been proposed.
For example, Japanese Unexamined Patent Application Publication No. H09-218014 discloses a device which generates three-dimensional information including distance information of each point on an object based on two data pieces of images captured by a pair of cameras provided at different positions, and identifies the object state based on the three-dimensional information.
International Publication No. 2010/140613 discloses a device which calculates feature values by creating a histogram from feature points of distance information (three-dimensional information) of each point on an object, obtained from a time-of-flight (TOF) camera, and compares the feature value with a reference pattern to identify the object.
Japanese Unexamined Patent Application Publication No. 2012-123781 discloses an apparatus which calculates three-dimensional coordinates of an object from two-dimensional information and distance information of each point on the object, and matches the three-dimensional coordinates to three-dimensional model data serving as a reference pattern to identify the state of the object.
In conventional devices that identify the state of an object such as those disclosed in Japanese Unexamined Patent Application Publication No. H09-218014, International Publication No. 2010/140613 and Japanese Unexamined Patent Application Publication No. 2012-123781, feature points of the object are extracted from three-dimensional information obtained by capturing an image of the object, and the state of the object is identified based on the feature points.
In the conventional method, the state of the object is identified by pattern matching, and thus information on the shape of the object to be imaged is required to be known. Therefore, when the shape of an object is unknown, it is almost impossible to identify the state of the object.